Investigation of the link between drought-induced changes in the expression of a novel sterol biosynthesis gene and drought tolerance in soybean

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Abstract

Glycine max (soybean) is an important crop species globally as it is used as a protein-rich food
and feed crop and as a source of oils used in the food and biofuel industry. However, the
growth and yield of soybean is adversely affected by drought. Exposure of soybean to drought
leads to accumulation of reactive oxygen species (ROS) and cell membrane instability. Sterols
are membrane components that regulates membrane fluidity and permeability. Besides being
major components of the cell membranes, sterols such as lanosterol appear to play a role in
the regulation of ROS scavenging and some are precursors to brassinosteroids that act as
signaling molecules with hormonal function that regulate growth, development and
responses to abiotic stresses such as drought and salinity. In this study, the involvement of
plant sterols, also known as phytosterols, in the regulation of soybean responses to drought
stress was investigated in Glycine max by determining the effects of drought on the
expression of a candidate lanosterol synthase gene (Glyma08g24160) and the content of a
subset of phytosterols in soybean. The effects of inhibition of sterol synthesis on ROS
production and on superoxide dismutase (SOD), ascorbate peroxidase (APX), catalase (CAT)
and dehydroascorbate reductase (DHAR) were investigated. The concentration of hydrogen
peroxide (H2O2) as well as superoxide (O2?-) increased in response to drought and sterol
synthesis inhibition, however, O2?- concentration and sterol contents declined under drought
stress and sterol synthesis inhibition.